Stray blue crabs have been known to show up in a Maine lobster trap here and there. But scientists say the species, which is common in the mid-Atlantic, is showing up more frequently in the Gulf of Maine as waters warm.
Manomet and the Maine Department of Marine Fisheries are calling on fishermen to track and report their sightings and observations through an online survey.
Fishermen and members of the public have reported 24 blue crab sightings so far this year, and that's on top of the blue crabs that are routinely found in researchers' traps placed around the Casco and Damariscotta estuaries.
Juvenile blue crabs and females carrying eggs are among those spotted in Maine, said Jessie Batchelder, a project manager for Manomet's fisheries team. They've also been seen during the winter.
"We've also had reports of mating blue crabs, so they are reproducing here," she said. "Those are all indications that they aren't just transient, that they are here year round, and we're starting to see a larger population."
It's too early to say whether the blue crab population has become a well-established population across the Maine coast, Batchelder said, but pockets are showing up in warmer estuaries.
Blue crabs are aggressive and tend to prey on young lobsters and shellfish, and Batchelder said a growing population could pose a threat to Maine's iconic lobster fishery, as well as oyster farmers and clam diggers. But scientists are studying whether blue crabs also have the potential to become a new, economically-viable fishery in Maine, Batchelder said.
"We don't have answers to those questions yet," she said. "But on the flip side, blue crabs farther south, everyone thinks of Chesapeake blue crabs and it's really popular fishery. People love to eat them. So if we are seeing more blue crabs and we get to that point, there may be an opportunity for a new fishery and a market for that there as well."
Anyone can report a blue crab sighting through a Manomet survey here.
